Depends what you mean by Christmas. If you go around, say the 22nd through New Years, it is a mad-house. We like to go between the 12th and the 21st, where the crowds are more or less moderate and nothing to write home about. My wife and I work for a University, and we also have only small windows when we can travel. Having done both summer and Christmas, we'll never do summer again. Being hot and sweltering in the humidity, dodging showers, just isn't enjoyable for us. Plus, the Christmas ambiance is great. Planned ride refurbishments typically begin after New years, so that shouldn't be an issue for most attractions.